Abstract: Water samples were collected from the upstream to the downstream of Hunhe River and its main tributaries in low flow period (April), flood period (August), and level period (November) in 2009, and the variations of their NH₄⁺-N, total phosphorus (TP), and heavy metals concentrations within a hydrological year were analyzed, aimed to study the pollution characters and sources of the water bodies. It was found that in the downstream (Qijianfang-Yujiafang) of Hunhe River, NH₄⁺-N had a high concentration (>1.5 mg·L^-1), with the water quality belonging to level Ⅴ, but the TP concentration was lower, with an average of 0.16 mg·L^-1. With the exception of Beizamu, Ajibu, Zhangdanghekou, and Yutai sites, the TP concentration at most sites was lower in level period (0.03-0.26 mg·L^-1) and flood period (0-0.25 mg·L^-1) than in low flow period (0.13-0.28 mg·L^-1). The measurements of the NH₄⁺-N and TP concentrations suggested that the water body of Hunhe River was more affected by the point source pollution of N and P. The Cu, Zn, Cd, and Pb concentrations in the surface water were 0.68-21.81, 43.33-129.00, 0.26-1.21, and 0-0.28 μg·L^-1, respectively, suggesting that the Hunhe River was slightly contaminated by these heavy metals. Overall, the water body of Hunhe River was more seriously point source polluted by urban domestic sewage and industrial wastewater, and thus, the management of drainage point source, illegal drainage point in particular, should be strengthened.

Key words: Clay-complex system, Red tide organisms, Removal efficiency, Penaeus japonicus, Toxic test